IMO, "the meaning of life" is to experience as many moments of joy as possible - that doesn't come at others' expense. And in my experience, the thing that brings more moments of joy is leading others towards joy. Big things like helping out a sick friend, or little things like throwing a dinner, giving a compliment, holding the door for someone. You can attract joy, and grow joy around you.

I was in line at the convenience store the other day - girl in front of me checked out, and accidentally dropped a folded stack of cash on the floor and started to leave. No idea how much it was, but I grabbed it and said "hey, miss - " The look on her face - surprise, relief, the sort of pure shock that someone looked out for her over themselves, big eyes and a huge smile - that still makes me happy. And maybe it helped her want to make others have that look on their face, no idea. But probably.